high-ranking official from the Archdiocese of Boston yesterday raised the possibility that the church will miss tomorrow's deadline for a settlement proposal to hundreds of alleged victims of sexual abuse -- despite a recent pledge by Bishop Richard G. Lennon that a such an offer would be made this week.

''I think there is a serious commitment to making a settlement, and negotiations are going on,'' Chancellor David W. Smith said in an interview with the Globe. ''Whether it will be Friday or next Tuesday or three weeks from Tuesday, I don't know.''

Tomorrow marks the end of the fourth voluntary mutual stoppage of litigation in about 400 of the 500 civil claims brought against the archdiocese by alleged victims of clergy sexual abuse. Lawyers for the plaintiffs agreed to the current 30-day halt after a personal appeal from Lennon, who asked for more time to reach a settlement after a 90-day moratorium expired last month without one.

Lennon, the interim head of the archdiocese who took over after Cardinal Bernard F. Law resigned, raised expectations for a settlement at a meeting of the US Conference of Catholic Bishops last week in St. Louis. Lennon said he believed church officials would be able to make a settlement offer by the end of this week.

Smith, however, said problems the archdiocese has had with its insurance companies, Travelers and Kemper, or other issues could make that impossible.

''If it doesn't happen by Friday, it won't be because we didn't do everything to make it happen,'' Smith said. ''It may be that a recalcitrant insurer, or a recalcitrant counsel, is the reason we don't have something fully baked by Friday afternoon. But it will not be because everyone isn't serious about settling it as soon as possible.''

Smith said both sides believe the settlement process ''should not be interrupted by an artificial timeline'' and said he is confident that if the deadline is missed lawyers for the church and alleged victims will go before Superior Court Judge Constance M. Sweeney, who is presiding over the hundreds of civil claims against the archdiocese, to ask for more time.

A lead lawyer for the plaintiffs, however, said yesterday that there is no sentiment on the plaintiffs' side for a further extension. After tomorrow, Boston attorney Jeffrey Newman said, lawyers for alleged victims will listen to any settlement offer from the archdiocese, but will not agree to any further delay in litigating their clients' cases in court.

''For the last year, the church has simply come to us and asked us to stop litigating and said, `Trust us,' '' said Newman, whose law firm, Greenberg Traurig, represents more than 200 people with claims against the archdiocese. ''Now, after 120 days of standing down, the church still isn't telling us where they are going with this. While our door is always open for discussion, and we will listen to any reasonable proposals, we have no choice now but to press forward with litigation.''

Diane Nealon, a social worker hired by Greenberg Traurig, said that if the archdiocese does not back Lennon's pledge, plaintiffs who are already on edge over the near-drowning last week of abuse victim Patrick McSorley could be sent into a tailspin.

''There is a despair out there that we haven't seen in a while,'' Nealon said. ''All of our clients have issues with trust, and when he [Lennon] made that statement, it was the first glimmer of hope that many of them have had.''

Smith attempted to qualify Lennon's statement yesterday, suggesting that what the bishop said had been ''taken out of context'' and he was only expressing a hope -- not a certainty -- that a settlement offer would be forthcoming this week.

Smith said he believed Lennon was expressing that he was ''cautiously optimistic that these cases will be settled, and that they will be settled through the mediation process and that there will not be trials.''

But Newman said there was ''no lack of clarity'' in Lennon's statement.

A review of news accounts and a videotaped interview Lennon gave Thursday show that Lennon said both that he ''hoped'' and ''believed'' an offer would be forthcoming this week. ''I believe we will have some kind of an answer sometime next week,'' Lennon told news anchor R.D. Sahl of New England Cable News in an interview.